If you are getting a message about connection failure, all Jupyter Hub slots are currently in use. The duration of your Jupyter Notebook session is 1 hour. After that, the server will close, but your files will be autosaved (however, to be safe, save your work periodically).

We do not recommend this method of connection to the cluster because you get only one compute node. As a consequence, you miss out on the opportunity to run multiple jobs at once and experience a parallel speedup.

Do not run Jupyter Notebook servers on the login node. There is very little performance in the login node, and, in addition, your jobs will periodically get killed when they exceed the memory or CPU time quota.